1. Field of Invention
The present invention relates generally semiconductor circuits, and more particularly to making an electrical connection to a contact of a microelectronic component on substrate or a circuit board.
2. Description of the Related Art
The integration of semiconductor components in circuit boards is assuming ever-increasing importance in the further development of circuit board production techniques.
For the production of highly integrated circuit boards, microelectronic components, such as semiconductor chips, SMD resistors, or SMD capacitors, are integrated in individual layers of circuit boards to increase the functionality of the circuit board. When integrating a semiconductor chip on a circuit board, the semiconductor chip is glued on a layer of the circuit board via, for example, a printed-on adhesive or an adhesive tape. The chip is then buried with an Resin Coated Copper (RCC) laminate, a layer of epoxy that is not fully cross-linked, and a copper foil. After lamination, the chip is covered by the epoxy of the RCC laminate. A space, which is also filled by the epoxy of the RCC laminate, separates the chip contacts and the copper foil. The copper foil and the epoxy over the chip contacts are then removed using a laser drilling machine and the micro holes thereby produced are filled using a current-less and/or galvanic metallization technique. After the electrical connection is made between the electric contacts of the chip and the copper foil, the copper foil is structured for producing printed board circuit tracks.
The depth of the micro holes produced with the laser drilling machine depends on the laminating parameters, the thickness of the semiconductor chip, and the thickness of the epoxy coat. This dependence means that the diameters of the micro holes do not drop below 50 μm at a depth of 25 to 50 μm. If the aspect ratio (ratio of diameter to depth) of the holes is undesirable, in particular less than 1:2, the metallization baths used may no longer adequately flow in and out of the holes and the metallization may be defective.
The copper foil is generally also strengthened during metallization. During the subsequent structuring of the copper foil into circuit tracks, this strengthening process has a negative influence on the width of the circuit tracks structure. the sub-surface etching, which affects the structure width, increases with the coat thickness. Hence, the thicker the copper coat, the larger the structures to be produced.
With the ever-increasing reduction in contact center-to-center distances (pitch) of the semiconductor chips, the limitations of the conventional micro-hole technology become more and more apparent. If the distance between two contacts on the chip becomes too small, the micro holes can no longer be produced while keeping adequate insulating distance between the contacts. This results in short-circuits between the contacts, rendering the product unusable. Problems using the conventional micro hole diameters, problems have already been arising at a pitch of less than 120 μm.
What is needed is a method for the electrical contacting of one or a plurality of microelectronic components on a substrate or a circuit board that avoids the disadvantages associated with the micro holes and can be implemented at low cost.